Centralizes snap sizing and implements spec'd behavior. Three resize

ash/wm/workspace/snap_sizer.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ASH_WM_WORKSPACE_SNAP_SIZER_H_
+#define ASH_WM_WORKSPACE_SNAP_SIZER_H_
+#pragma once
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+#include "base/time.h"
+#include "ui/gfx/rect.h"
+
+namespace aura {
+class Window;
+}
+
+namespace ash {
+namespace internal {
+
+// SnapSizer is responsible for determining the resulting bounds of a window
+// that is being snapped to the left or right side of the screen.
+class ASH_EXPORT SnapSizer {
+ public:
+  enum Edge {
+    LEFT_EDGE,
+    RIGHT_EDGE
+  };
+
+  SnapSizer(aura::Window* window,
+            const gfx::Point& start,
+            Edge edge,
+            int grid_size);
+
+  // Updates the target bounds based on a mouse move.
+  void Update(const gfx::Point& location);
+
+  // Bounds to position the window at.
+  const gfx::Rect& target_bounds() const { return target_bounds_; }
+
+ private:
+  // Calculates the amount to increment by. This returns one of -1, 0 or 1 and
+  // is intended to by applied to |percent_index_|. |x| is the current
+  // x-coordinate, and |reference_x| is used to determine whether to increase
+  // or decrease the position. It's one of |last_adjust_x_| or |last_update_x_|.
+  int CalculateIncrement(int x, int reference_x) const;
+
+  // Changes the bounds. |x| is the current x-coordinate and |delta| the amount
+  // to increase by. |delta| comes from CalculateIncrement() and is applied
+  // to |percent_index_|.
+  void ChangeBounds(int x, int delta);
+
+  // Returns the target bounds based on the edge and |percent_index_|.
+  gfx::Rect GetTargetBounds() const;
+
+  // Returns true if the specified point is along the edge of the screen.
+  bool AlongEdge(int x) const;
+
+  // Window being snapped.
+  aura::Window* window_;
+
+  const Edge edge_;
+  const int grid_size_;
+
+  // Current target bounds for the snap.
+  gfx::Rect target_bounds_;
+
+  // Time Update() was last invoked.
+  base::TimeTicks time_last_update_;
+
+  // Index into |kPercents| that dictates the width of the screen the target
+  // bounds should get.
+  int percent_index_;
+
+  // Number of times Update() has been invoked since last ChangeBounds().
+  int num_moves_since_adjust_;
+
+  // X-coordinate the last time ChangeBounds() was invoked.
+  int last_adjust_x_;
+
+  // X-coordinate last supplied to Update().
+  int last_update_x_;
+
+  DISALLOW_COPY_AND_ASSIGN(SnapSizer);
+};
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_WM_WORKSPACE_SNAP_SIZER_H_